As is well known, planes typically travel at significant speeds at the point of landing. To accommodate these speeds, wheels are provided on the aircraft landing gear such that the aircraft continues to move after the plane lands on the runway. Braking forces may then be applied either to the wheels or by means of jet reversers to bring the plane to a stop.
Considering the wheels in more detail, when in flight, the wheels are in a moving reference frame. In particular, the wheels have a velocity equal to the velocity of the plane just prior to impact relative to the surface on which the plane is landing. The typically large difference between the velocity of the wheel and velocity of the surface on which the plane is landing generates significant frictional forces between the surface of the wheel's tire and the landing surface. Initially the velocity of the tire relative to the landing surface is great enough to overcome the sliding friction between the tire and the landing surface. This causes the tire to slide until the tire has decelerated sufficiently for rolling frictional forces to take over. This initial sliding is evident from an audible chirp or screech made as the plane touches down. During the sliding phase, as the tire is essentially dragged across the landing surface, the landing surface abrades the tire at the contact patch leading to a flat spot on the tire. As will be appreciated such “flat spotting” of the tire makes the tire out of round decreasing its performance during the rolling phase. Repeated flatspotting greatly shortens the useful life of the tire.
As will be appreciated, the significant downforce of the plane exacerbates the wear of the tire. As a result, the frictional forces coupled with the downward force of the plane results in a great amount of wear and tear on the tire. This wear requires frequent replacement of the tires and increases the amount of downtime for the plane.